<template>
  <div class="channel-edit">
    <van-cell center :border="false">
      <div slot="title" class="channel-title">我的频道</div>
      <van-button
        type="danger"
        plain
        round
        size="mini"
        @click="isEdit = !isEdit"
        >{{ isEdit ? "完成" : "编辑" }}</van-button
      >
    </van-cell>

    <!-- :class="{active:index===激活的频道}"  -->
    <van-grid :gutter="10">
      <van-grid-item
        class="grid-item"
        :class="{ active: index === active }"
        :icon="isEdit && index !== 0 ? 'clear' : ''"
        v-for="(channel, index) in userChannels"
        :key="index"
        :text="channel.name"
        @click="onUserChannelClick(channel, index)"
      />
    </van-grid>

    <van-cell center :border="false">
      <div slot="title" class="channel-title">频道推荐</div>
    </van-cell>
    <van-grid :gutter="10">
      <van-grid-item
        class="grid-item"
        v-for="(channel, index) in recommendChannels"
        :key="index"
        :text="channel.name"
        @click="onAdd(channel)"
      >
      </van-grid-item>
    </van-grid>
  </div>
</template>

<script>
import {
  getAllChannels,
  addUserChannel,
  deleteUserChannel,
} from "@/api/channel";
import { mapState } from "vuex";
import { setItem } from "@/utils/storage";
export default {
  // 组件名称
  name: "ChannelEdit",
  // 组件参数 接收来自父组件的数据
  props: {
    userChannels: {
      type: Array,
      required: true,
    },
    active: {
      type: Number,
      required: true,
    },
  },
  // 局部注册的组件
  components: {},
  // 组件状态值
  data() {
    return {
      allchannels: [], //所有频道数据列表
      isEdit: false, //控制编辑的显示状态
    };
  },
  // 计算属性
  computed: {
    ...mapState(["user"]),
    //推荐的频道列表
    //计算属性会观测内部依赖数据的变化而重新求值
    recommendChannels() {
      //所有频道-我的频道=剩余推荐频道
      //filter方法，过滤数据，数据方法返回的布尔值，true收集数据
      //查找满足条件的所有元素
      return this.allchannels.filter((channel) => {
        //判断channel是否属于用户频道
        //find方法查找满足条件的单个元素
        return !this.userChannels.find((userChannel) => {
          //找到满足条件的元素
          return userChannel.id === channel.id;
        });
      });
    },
  },
  // 侦听器
  watch: {},
  created() {
    this.loadAllChannels();
  },
  mounted() {},
  // 组件方法
  methods: {
    async loadAllChannels() {
      const { data } = await getAllChannels();
      this.allchannels = data.data.channels;
    },
    async onAdd(channel) {
      this.userChannels.push(channel);

      //TODO:数据持久化
      if (this.user) {
        //登陆了，数据存储到线上
        await addUserChannel({
          channels: [
            {
              id: channel.id,
              seq: this.userChannels.length,
            },
          ],
        });
      } else {
        //没有登陆，存储到本地
        setItem("user-channels", this.userChannels);
      }
    },
    onUserChannelClick(channel, index) {
      if (this.isEdit && index !== 0) {
        //编辑状态，删除频道
        this.deleteChannel(channel, index);
      } else {
        //非编辑状态，切换频道
        this.switchChannel(index);
      }
    },
    async deleteChannel(channel, index) {
      //如果删除的是当前激活频道之前的频道
      if (index <= this.active) {
        //更新激活频道的索引
        this.$emit("update-cative", this.active - 1);
      }
      this.userChannels.splice(index, 1);

      //数据持久化
      if (this.user) {
        //登陆了，持久化到线上
        await deleteUserChannel(channel.id);
      } else {
        //未登录，持久化到本地
        setItem("user-channels", this.userChannels);
      }
    },
    switchChannel(index) {
      //切换频道
      this.$emit("update-active", index);

      //关闭弹出层
      this.$emit("close");
    },
  },
};
</script>

<style scoped lang='less'>
.channel-edit {
  padding-top: 54px;

  .channel-title {
    font-size: 16px;
    color: #333333;
  }

  .grid-item {
    width: 80px;
    height: 43px;

    /deep/ .van-grid-item__content {
      background-color: #f4f5f6;

      .van-grid-item__text {
        font-size: 14px;
        color: #222222;
        margin-top: 0;
      }
    }

    /deep/ .van-grid-item__icon {
      position: absolute;
      right: -10px;
      top: -5px;
      font-size: 20px;
      color: #cccccc;
    }
  }

  .active {
    /deep/ .van-grid-item__text {
      color: red !important;
    }
  }
}
</style>